• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.337-349
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• 1996

A study was conducted to find the possible relationship between slip distance and dynamic coefficient of friction (DCOF) through the biomechanical study of slips and falls using a broader variety of floors and levels of slipperiness than those used before. Four different floor surfaces covering the full range of floor slipperiness (with and without on oil contaminant) were prepared for ten subjects with each walking at a fixed velocity. The results showed that slip distance and heel velocity had a decreasing trend while stride length had a increasing trend as DCOF increased. The contaminant effect overpowered floor slipperiness effect because a higher DCOF surface with oil contaminant created longer slip distance than the lower DCOF with dry floor. Normal gait pattern and suggested heel velocity (10 to 20 cm/sec) were seen on dry floors but abnormally longer stride length and 5 to 10 times faster heel velocity were found an oily floors. In other words, faster heel velocity (greater than 10 to 20 cm/sec) is recommended to measure DCOF on oily floors because the assumption of normal gait was no longer valid.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.2
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• pp.197-202
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• 2001

The biomechanical analysis of the load carrying effect on different floor surfaces has been conducted. Four different floor surfaces were prepared for ten subjects with each walking at a fixed velocity(1.33 m/sec) while carrying five different loads. The results showed that because of the significant interaction effect between floor slipperiness and the load carrying task, the load carrying effect should be analyzed according to different levels of the floor slipperiness, especially contaminant floors. On oily surfaces, slip distance(SD) and heel velocity (HV) increased whereas stride length(SL) decreased as load increased. In other words, significantly longer SD, faster HV, and no normal gait were found as load increased. As a result, a different protocol should be applied to measure floor slipperiness on oily floors as compared to dry surfaces for tribological approach.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.126-133
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• 2013

Recently, it was reported that complaints about problems being experienced with the performance of vehicles operating on autogas in Korea. The problem was being assumed due to contaminants in LPG and an oily material which was being deposited in vaporizer, injector in LPG fuel system. This study is focused on the analysis of contaminant of automobile parts on LPG fuel system. The sampling points of contaminants are injectors, fuel filters, vaporizer in automobile equipment and it was also investigated by GC-MS, ICP-AES, SIMDIS and EDS. According to results, it was presumed that this contaminants had been analyzed plasticizers with hydrocarbons with high boiling point, Fe from steel corrosion, greases from gas station.

• Advances in environmental research
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• v.4 no.2
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• pp.69-81
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• 2015

A new magnetite-silica core/shell nanocomposite ($Fe_3O4@nSiO_2@mSiO_2$) was synthesized and functionalized with trimethylchlorosilane (TMCS). The prepared nanocomposite was used for the removal of diesel oil from aqueous media. The characterization of magnetite-silica nanocomposite was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), surface area measurement, and vibrating sample magnetization (VSM). Results have shown that the desired structure was obtained and surface modification was successfully carried out. FTIR analysis has confirmed the presence of TMCS on the surface of magnetite silica nanocomposites. The low- angle XRD pattern of nanocomposites indicated the mesoscopic structure of silica shell. Furthermore, TEM results have shown the core/shell structure with porous silica shell. Adsorption kinetic studies indicated that the nanocomposite was able to remove 80% of the oil contaminant during 2 h and fit well with the pseudo-second order model. Equilibrium studies at room temperature showed that the experimental data fitted well with Freundlich isotherm. The magnetic property of nanocomposite facilitated the separation of solid phase from aqueous solution.

• Geomechanics and Engineering
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• v.20 no.3
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• pp.207-220
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• 2020

Clay soils have a big potential to become contaminated with the oil derivatives because they cover a vast area of the earth. The oil derivatives diffusion in the soil lead to soil contamination and changes the physical and mechanical properties of the soil specially clay soils. Soil stabilization by using new material is very important for geotechnical engineers in order to improve the engineering properties of the soil. The main subjects of this research are a- to investigate the effect of the cement and epoxy resin mixtures on the stabilization and on the mechanical parameters as well as the microstructural properties of clay soils contaminated with gasoline and kerosene, b- study on the phenomenon of clay concrete development. Practical engineering indexes such as Unconfined Compressive Strength (UCS), elastic modulus, toughness, elastic and plastic strains are all obtained during the course of experiments and are used to determine the optimum amount of additives (cement and epoxy resin) to reach a practical stabilization method. Microstructural tests were also conducted on the specimens to study the changes in the nature and texture of the soil. Results obtained indicated that by adding epoxy resin to the contaminated soil specimens, the strength and deformational properties are increased from 100 to 1500 times as that of original soils. Further, the UCS of some stabilized specimens reached 40 MPa which exceeded the strength of normal concrete. It is interesting to note that, in contrast to the normal concrete, the strength and deformational properties of such stabilized specimens (including UCS, toughness and strain at failure) are simultaneously increased which further indicate on suitability and applicability of the current stabilization method. It was also observed that increasing cement additive to the soil has negligible effect on the contaminated soils stabilized by epoxy resin. In addition, the epoxy resin showed a very good and satisfactory workability for the weakest and the most sensitive soils contaminated with oil derivatives.

• Membrane and Water Treatment
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• v.6 no.6
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• pp.489-499
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• 2015

In this work, treatment of real hypersaline refinery wastewater by hollow fiber membrane bioreactor coupled with reverse osmosis unit was studied. The ability of HF-MBR and RO developed in this work, was evaluated through examination of the effluent properties under various operating conditions including hydraulic retention time and flux. Arak refinery wastewater was employed as influent of the bioreactor which consists of an immersed ultrafiltation membrane. The HF-MBR/RO was run for 6 months. Average elimination performance of chemical oxygen demand, biological oxygen demand, total suspended solids, volatile suspended solids, total dissolved soild and turbidity were obtained 82%, 89%, 98%, 99%, 99% and 98% respectively. Highly removal performance of oily contaminant, TDS and the complete retention of suspends solids implies good potential of the HF-MBR/RO system for wastewater refinement.

• Clean Technology
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• v.10 no.3
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• pp.121-130
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• 2004

Pelletizer of dry ice snow produced by adiabatic expansion of liquid carbon dioxide and their blaster were designed and manufactured. The blaster had a high cleaning power against various contaminants on the surface such as stain, oily dirt, lacquer film and paints with low blasting pressure and low consumption of blasting air. The capacity of hopper for dry ice pellet supply was 12 kg and the mass rate of pellet blasting was controlled in 0 to 1.2 kg/min. The impact of the pellets was independent of standoff distance within a certain limiting distance, and dependent on the impact stress, angle and mass rate of dry ice pellet blasting. On the other hand the cleaning power was influenced by thermal properties and surface roughness of the substrates and decreased in the order of glass, copper, brass, steel and acryl. The power was also affected by hardness and adhesion of the contaminant on the substrate, and decreased in the order of grease, epoxy and paint. The noise was detected during blasting in the range of 85 to 100dBA.